Complexity of emergency-only baseband firmware development
denver at ossguy.com
Fri Mar 10 20:22:06 UTC 2017
On Fri, Mar 10, 2017 at 11:49:53AM -0800, Mychaela Falconia wrote:
> > Eventually
> > I would like to be able to bundle these tools with a phone that runs only
> > free software.
> A phone that runs only free software? What kind of phone would it be
> hardware-wise: do you plan on building your own hw, or are you trying
> to repurpose/reprogram some existing phone hw units?
It would be great if I could find some existing hardware instead of building my own. The Neo FreeRunner seems like a good candidate given what you said later (more on that below).
> Not just to Denver but to everyone: please remember that with *ANY*
> libre or FOSS phone goal, the software is the easy part; the hard part
> is the hardware.
I've created (rather unsophisticated) hardware in the past (see http://ossguy.com/ss_usb/ ). I realize that building a phone is a substantial undertaking so I'd like to avoid that if possible.
> The *only* hardware feature which can be omitted if you wish to limit
> cell functionality to emergency calls only is the SIM socket. The SIM
> socket I use on the FCDEV3B costs $2.12 in quantity 1 at Digi-Key (or
> down to $1.38 per piece when buying 1000-piece reels), and my opinion
> is that if you omit the SIM socket on your phone in order to
> *artificially* restrict its cellular capabilities to emergency calls
> only, you are being antisocial by artificially hobbling your product
> to suit your particular prejudices.
I would be fine with retaining the SIM socket in whichever solution I eventually end up using.
> > My understanding from being on the list for a while is that the current
> > baseband firmware works for some basic use cases on existing phones,
> Not just for "some basic use cases", but 100% of standard commercial
> GSM+GPRS modem functionality:
> if you have a Neo Freerunner made by
> Openmoko, the Calypso GSM+GPRS modem included in that product provided
> full commercial quality implementation of all standard GSM and GPRS
> functionality with the official firmware those units shipped with, and
> this full functionality is retained without any degradation if you
> replace their original proprietary firmware with FC Magnetite.
I do have a Neo FreeRunner so perhaps that should be my first goal: to run FC Magnetite and see how well it works for me.
> Our Magnetite firmware has not been fully deblobbed yet, but:
> * We have a clear roadmap toward a fully deblobbed version;
Does it seem like a substantial amount of work? Or is there not much left now?
> 1: Neo Freerunner by Openmoko. This hw is where the original
> FreeCalypso project started, and has the best support. But the
> Freerunner is not a bare modem or a dumbphone, it also has a Linux
> application processor that requires very complex software to make
> it usable as a phone, and the community that once maintained this
> complex sw is now gone. Without an active community of developers
> to maintain that Linux AP software, the Freerunner makes a very
> poor choice of phone: it is too complex and too power-hungry to
> serve as a dumbphone substitute, yet it does not really offer
> anything of practical value that a proper dumbphone can't do, thus
> it is neither here nor there - "neither fish not meat" as the
> Russian saying goes.
Would it not still offer wifi support? If so, then it seems to be a good candidate for my use case. And I would be unlikely to find a dumbphone that would do wifi anyway.
Of course, as you said, the community is mostly gone at this point. Bringing that back would be a challenge, but if I was able to work on the FreeRunner software full-time for a while, perhaps I could make that happen.
> if the people who have funded
> the current FCDEV3B effort wish to continue further in this direction,
> we can produce a FreeCalypso modem in a packaged form factor similar
> to SIM900 etc, and the liberated firmware for this mode of operation
> is already here and 100% functional.
That would be an excellent way forward if for some reason the FreeRunner is not suitable.
> > So I'd be curious to know if the emergency-only use case is substantially
> > easier to develop for, or if it's roughly the same complexity as developing
> > for the all-purpose use case, or somewhere in between.
> In terms of software, the emergency-only use case is more complex
> because you would have to do extra work to remove perfectly good and
> working code for non-emergency functionality.
Thanks for clarifying that. I have no intention of spending time removing such functionality - it seems fine to leave it in and retain the SIM card slot as discussed.
> I hope my answers clarify things for you a little.
They certainly do! Thank-you very much.
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